33 6 DISCOVERY REPORTS 



Station WS 469. 10. xi. 29. Lat. 56 42' S. Long. 57 00' W. 3959 m. (Plate XVII.) 

 Diatomaceous mud. Essentially similar to the foregoing sample but perhaps containing more 

 broken tests of Globigerina. 



Station WS 470. 11. xi. 29. Lat. 57 50' S. Long. 57 27' W. 3572 m. (Plate XVII.) 

 Diatomaceous mud. The sample consists of a few black pebbles with a small quantity of sediment. 

 The latter is composed mainly of quartz grains which average about 0-05 mm. in diameter, but some 

 reach 0-2 mm. and more, together with occasional grains of green hornblende. A colourless mineral, 

 in cross-shaped twin crystals about 0-05 mm. in length, with low refractive index (about 1-50) and 

 low birefringence is referred to phillipsite. Sponge spicules and the diatoms Coscinodiscus and 

 Fragilaria are comparatively plentiful. 



Station WS 471. 12. xi. 29. Lat. 58 53' S. Long. 57" 54' W. 3762 m. (Plate XVII.) 

 Diatomaceous mud. This deposit, fine grained and brown in colour, is typical of its class. Mineral 

 grains are usually small (less than 0-05 mm.), though some reach a diameter of 0-2 mm. ; quartz, 

 green hornblende and hypersthene are noted. Diatoms are present in fair variety, including species of 

 Coscinodiscus, Cocconeis, Fragilaria and Thalassiothrix. Comminuted frustules form part of the 

 finest material, the particles of which often cohere in flocculent masses. Radiolarian and foraminiferal 

 tests are seen occasionally. 



Station WS 472. 12. xi. 29. Lat. 59 42V S. Long. 58 01' W. 3580 m. (Plate XVII.) 

 Diatomaceous mud. There is a fair amount of flocculent material composed of diatom frustules 

 and other organic debris; the chief genera are Coscinodiscus and Fragilaria. Mineral grains, chiefly 

 quartz and green hornblende, vary in size from o-i mm. to less than o-oi mm. in diameter. 



Station WS 474. 13. xi. 29. Lat. 6i° 03' S. Long. 56° 42' W. 2813 m. (Plate XVII.) 

 Diatomaceous mud. The coarser fraction consists of mineral grains, ranging from 0-5 to less than 



001 mm. in diameter. Angular to rounded grains of quartz and green hornblende are prominent. 



Among the diatoms, Coscinodiscus is large (up to 0-2 mm.) and abundant. Other genera include 



Thalassiosira and Fragilaria. Sponge spicules and broken frustules of diatoms contribute to the 



flocculent aggregates of the finer material. 



Station WS 475. 14. xi. 29. Lat. 6i° 48' S. Long. 55 51' W. 1047 m. (Plate XX.) 

 Diatomaceous mud. The chief feature of this dark grey mud is the fine-grained fraction, which 

 consists almost entirely of diatom remains — chiefly fragmentary frustules; but many entire tests 

 occur, some of which retain their greenish cell contents. Species of Coscinodiscus (up to 0-2 mm. 

 diameter), Cocconeis, Fragilaria, Rhizosolenia are the most abundant forms. Mineral grains up to 

 0-25 mm. in diameter form a subordinate fraction of the deposit; the quartz grains are more or less 

 rounded, but splinters of vesicular volcanic glass are sharply angular; there are also flakes of white 

 mica, 0-25 mm. across. 



Station WS 476. 14. xi. 29. Lat. 62 16' S. Long. 58 18' W. 542 in. (Plate XX.) 

 Terrigenous mud. In this dark grey mud organic remains are scanty, and chiefly consist of small 

 diatom frustules in the finer material. The coarser fraction consists of subangular mineral grains the 

 size of which ranges downwards from a diameter of about 0-2 mm. Quartz, felspar, green hornblende 

 and volcanic glass are noted. 



Station WS 477. 14. xi. 29. Lat. 62 2o£' S. Long. 58 14' W. 1892 m. (Plate XX.) 

 Terrigenous mud. The bulk of this sample is formed of small angular mineral grains whose 



diameter is less than o-oi mm., but there is a fair proportion of larger grains up to about o-i mm. 



across. Hence the deposit is classed as a terrigenous mud although diatoms are by no means rare. 



The genera Coscinodiscus, Cocconeis, Fragilaria, Rhizosolenia and Corethron are represented. The 



mineral constituent includes grains of quartz, green hornblende and volcanic glass. 



